In the conscious dog we shall pursue the large-deformation analysis of the motion of the right heart. In order to gain insight into the physological meaning of large deformations we shall explore ther relationship between ventricular pressure and regional free-wall strains, such as these are determined from chronically-implanted radiopaque markers. Moreover, we shall attempt to reconcile the current physiological concepts of cardiac contraction with a stress-versus-strain-and pressure hypothesis. To this end we shall expand to three dimensions the following equation for stress in the heart wall: where (x) equals alpha(e Beta(x -x *) - 1) where (x) equal force/area, x equals muscle length, x* equals muscle resting length, and alpha, Beta equal elastic constants. This equation has been used previously to describe the elasticity of Cardiac muscle. Since our developed methematical and computational procedures yield accurate data on regional strains, the proposed research will lead to a better understanding of the distribution of regional stress in heart muscle. In particular, beat-to-beat information will be gained on the orientation of three-dimensional stresses in the right and left ventricles.